There will be described CAD, firstly. CAD (Computer Aided Design) systems are widely used in designing operations. CAD systems are also used for aiding drawing operations, after designing operations. Further, by the development of computers, CAD systems allow more sophisticated operations. Moreover, those situations where the features of CAD systems are maximally utilized include a situation where previously designed shapes are altered and utilized.
Further, 3-dimensional CAD applications are also practiced, in addition to 2-dimensional CAD applications. Geometric models in such 3-dimensional CAD applications include a wireframe model, a surface model and a solid model (see FIGS. 1A, 1B and 1C).
Firstly, the wireframe model relates to a method for expressing a shape, by a 3-dimensional body comprising ridge lines and apexes in a 3-dimensional space. It is also possible to consider that the wireframe model can be handled in a 3-dimensional space by adding Z values to a 2-dimensional geometric figure.
Next, the surface model relates to a method for expressing a shape, by a 3-dimensional body prepared by mutually attaching predetermined “series of ridge lines” each constituting a surface. Namely, this method is to express a 3-dimensional body based on a combination of surfaces, by defining each surface by information of a series of ridge lines constituting the boundaries of the surface.
As a result of containing information of surfaces, the application field of these models are being extremely widespread, such as to allow: application to bent surface processing; and preparation of cross-sectional views.
In the wireframe models and surface models as briefly described above, 3-dimensional bodies are expressed as lines or surfaces, so that those models have no information indicating where the entities are. For example, in those models prepared as surface models, it is impossible to determine whether the contents of the 3-dimensional shapes are hollow or solid.
Contrary, the solid model relates to a method for expressing a shape by a 3-dimensional body filled with contents and the solid model has the information indicating where the entity of the shape is, so that the solid model is capable of completely expressing the 3-dimensional body.
Simply giving data of a relative density to a 3-dimensional shape prepared by using a solid model is extremely effective in various applications, such as: mass property calculation of weight and center of gravity; checking of interference between parts; NC programming; mechanism analysis; shading; hidden-line-deleting display; and preparation of 2-dimensional drawings.
However, the data structure is complicated in solid models, thereby possibly causing practical limitations that the calculation burden of a computer is increased for modifying or displaying the shape, resulting in a prolonged processing time.
Meanwhile, in CAD systems, there has been developed a so-called parametric designing method for designing those parts which are mutually analogous and have different sizes. This is a method for automatically reconstructing geometric figures, by simply modifying dimension values.
Further, designing operations include so many geometric figures and parts to be repeatedly used. These are called “parts” and “figures”, for example. In solid modeler, these parts are combined in various windows to thereby perform a final design.
There will be now described windshield glass. Vehicular windshield glass is constituted of laminated glass, so as to ensure a field of view upon breakage of the windshield glass. Such laminated glass is provided by adhering two glass plates 50, 51 to each other via intermediate film 53 comprising thermoplastic resin such as polyvinyl butyral (see FIG. 2).
The two glass plates constituting the laminated glass are required to have substantially the same shapes, for adhering to each other.
As such, the two glass plates are cut out into predetermined dimensions from a flat blank plate manufactured by a float process, and then placed on a ring-like mold and transferred into a heating furnace. These two glass plates are heated in the furnace to the softening point of the glass, so that the two glass plates are deformed by the self-weights or are sagged by gravity, and given with predetermined shapes. At this time, the shapes of the two glass plates become substantially the same with each other, which is preferable for constituting the laminated glass.
Further, those widely used shapes of windshield glass frequently have largely bent right and left ends. In forming a flat glass plate into such a shape, it is frequently insufficient to use a simple ring-like mold. Thus, there has been developed and practiced a ring-like mold having divided right and left ends 61, 62 (see FIG. 3).
Meanwhile, various sizes and types of automobiles have the substantially same shapes of windshield glass. In many cases, only the sizes of windshield glass are analogously changed and/or the dimensions of particular portions are changed.
This allows to fabricate models of new molds by altering previously prepared models, in manufacturing new windshield glass.
There will be then described vehicular door glass and rear glass. Vehicular door glass and rear glass are frequently formed of tempered glass. Such tempered glass is obtained by: heating a glass plate up to temperatures near its softening point; and then quenching the glass plate by blowing air onto both surfaces of the glass plate.
For example, glass plates are: cut out into predetermined dimensions from a flat blank plate manufactured by a float process; transferred into a heating furnace so that the glass plates are heated therein; and taken out of the heating furnace and press-worked by a press-mold, to thereby obtain a predetermined shape. Thereafter, the glass plates are quenched so as to be tempered by a cooling process.
Further, those widely used shapes of rear glass frequently have largely bent right and left ends. In forming a flat glass plate into such a shape, it is frequently insufficient to use a simple ring-like mold. Thus, there has been developed and practiced a ring-like mold having divided right and left ends.
Meanwhile, shapes of vehicular door glass and rear glass can be classified into several representative shapes. Further, shapes themselves of vehicular door glass and rear glass are frequently applicable to anyone of the classified shapes, even when vehicular sizes and/or shapes are varied in themselves. In many cases, only the sizes of door glass and rear glass are analogously changed and/or the dimensions of particular portions thereof are changed, in the applicably classified shapes, respectively.
This allows to fabricate models of new molds by altering previously prepared models, in manufacturing new door glass or rear glass.
On the other hand, in developing vehicles, it has been required to further shorten the development time. Particularly, the development time for those types of vehicles using common platforms (chassis) is further shortened, as compared with those vehicles using newly developed platforms. As such, there has been required a faster response within a further shortened delivery period, also in manufacturing windshield glass, door glass, or rear glass.
To cope with the above, it is effective to alter those existing mold models. However, in altering mold models by utilizing 3-dimensional CAD applications, it will be an extremely inefficient operation to alter and modify individual parts constituting the mold in accordance with the altering conditions, part by part.
Further, it is also required to consider constraint conditions such as mutual interference among parts, thereby frequently making it difficult to conduct the altering and modifying operations therefor within a short time.
Moreover, modifying dimensions of a certain part problematically requires many man-hours, in order to precisely reflect the consequence to other parts, for example. Thus, even when existing mold models have been altered, it has been difficult to evaluate whether such alterations achieve the intended designing purpose or not.